The specific aims of this proposal are to study effects of calcium translocations on renal hemodynamics and function in experiments employing calcium ionophores and channel-blocking agents, utilizing an isolated perfused rat kidney preparation. Calcium-dependent "agonists" and "antagonists" will be added to perfusate and their effects on function of kidneys obtained from normal Wistar rats assessed. The results will be compared to data from similar experiments performed on kidneys obtained from Kyoto spontaneously hypertensive rats, as well as normotensive Wistar-Kyoto controls. The effects of antihypertensive treatment on renal responses to calcium "agonists" and "antagonists" also will be studied. Finally, the effects of the "agonists" and "antagonists" in Dahl salt-sensitive hypertensive rats prepared on low and high-sodium diets will be determined, and compared with results obtained on kidneys from normotensive salt-resistant Dahl rats. The proposed studies will permit a detailed assessment of the effect of calcium "antagonists" on renal function in normotensive and hypertensive rat models. The studies are needed because drugs of this class will come into wide usage during the next several years. In addition, the proposed studies will elucidate the role of calcium in the pathogenesis of certain animal models of hypertension, and may relate to the pathogenesis of human hypertension and the role of salt in hypertensive disease.